BUT HE IS OKAY. THE PILOT DIED LATER THAT NIGHT. IT WAS A YEAR AGO TONIGHT THAT A 19-YEAR-OLD UNH STUDENT WAS SEEN FOR THE LAST TIME. LIZI MARRIOTT WAS SOON REPORTED MISSING AND THE CASE QUICKLY TURNED INTO A MURDER INVESTIGATION WITH TRAGIC DETAILS THAT INCLUDED HER BODY BEING DUMPED INTO A RIVER IN PORTSMOUTH. HER BODY HAS NEVER BEEN RECOVERED. AND NOW THE STATE IS PREPARING FOR A MURDER TRIAL UNLIKE MOST THAT WE SEE HERE IN NEW HAMPSHIRE. TONIGHT OUR AMY COVENO TAKES A CLOSE LOOK AT THE INVESTIGATION AND THE CHALLENGES FACING PROSECUTORS. TOGETHER WE CREATED AN ANGEL. AND SHE IS HOME IN HEAVEN. A FATHER'S ANGUISH HEARD AND FELT AT A MEMORIAL SERVICE FOR HIS 19-YEAR-OLD DAUGHTER. ON OCTOBER 13, 2012, POLICE ANNOUNCED THE COLLEGE STUDENT WAS DEAD, AND 29-YEAR-OLD SETH MAZZAGLIA WAS THE CUSTODY. CHARGED WITH HER MURDER. THE COMPLAINT ALLEGES THAT HE RECKLESSLY CAUSED THE DEATH OF ELIZABETH LIZZI MARRIOTT UNDER CIRCUMSTANCES MANIFESTING IN EXTREME INDIFFERENCE TO THE VALUE OF HUMAN LIFE. AS DETAILS OF HER LAST NIGHT OF LIFE EMERGED, THE GRIEVING FAMILY STRUGGLED FOR CLEAR, NO REMAINS TO BURY, NO FINAL LOOK, KISS OR GOOD-BYE. FOR INVESTIGATORS, A COMPLEX CASE TO BRING TO TRIAL. A MURDER WITHOUT A BODY. IT'S ONLY HAPPENED ONCE OR TWICE IN NEW HAMPSHIRE'S HISTORY. SO MANY TIMES THE WAY SOMEONE IS KILLED PROVIDES VALUABLE EVIDENCE ABOUT THE MENTAL STATE OF THE PERSON THAT INFLICTED THE INJURIES. THE STATE DOESN'T HAVE THAT IN IN CASE, BECAUSE THEY DON'T HAVE AN AUTOPSY, THEY DON'T HAVE A MEDICAL EXAMINER THAT WILL BE ABLE TO SAY HOW THE VICTIM WAS KILLED. WHAT INVESTIGATORS DO HAVE, STATEMENTS MADE TO POLICE BY THEIR PRIME SUSPECT, SETH MAZZAGLIA, WHO IN GRAPHIC AT THE DETAIL DESCRIBED WHAT UNFOLDED INSIDE THIS DOVER PART ON THE NIGHT OF OCTOBER 9. MAZZAGLIA, HIS GIRLFRIEND CAT MCDONOUGH AND LIZZI WERE PLAYING STRIP POKER, HE CLAIMS. THE CONVERSATION TURNED TO SADO MASS KENTUCKY AND THE THREE EVENTUALLY ENGAGED IN GROUP SEX, CONSENSUAL SEX, THAT INVOLVED A ROPE AROUND HER NECK, CHOKING HER DURING INTERCOURSE. SHE HAD A SEIZURE AND THEY WATCHED UNTIL SHE STOPPED BREATHING. FORENSIC EVIDENCE WAS GATHERED FROM HIS APARTMENT, BUT THEY MAY JUST LINK HIM TO HER DISAPPEARANCE. IT MAY NOT BE ENOUGH TO PROVE EXACTLY WHAT HAPPENED AND HOW IT HAPPENED. BUT COURT DOCUMENTS REVEAL MAZZAGLIA E LAB RATED ON HOW HE AND CAT MCDONOUGH DUMPED THE BODY. HE SAID THEY DROVE TO PIERCE ISLAND, DRAGGED HER BODY TO AN OVERLOOK AND PUSHED IT INTO THE WATER. THE AFFIDAVIT STATES HER BODY DID NOT SINK, SO MCDONOUGH COMPLETED THE TASK, MAKING THE CRUDE JOKE ABOUT DAVEY JONES' LOCKER. HER BODY HAS NEVER BEEN FOUND. IN CASES LIKE THIS, EXPERTS SAY THE HARSH CRUEL TASK OF PROVING LIZZI IS REALLY DEAD FALLS BACK ON HER FAMILY. IT'S DIFFICULT TO DEFEND, BECAUSE JURORS ARE OFTEN PRESENTED WITH VERY EMOTIONAL TESTIMONY, IN THIS CASE PROBABLY FAMILY MEMBERS LEFT TO TALK ABOUT THE FACT THAT THEY HAVEN'T SEEN HER, TO ESTABLISH THAT SHE'S NOT THERE. AND THAT'S VERY DIFFICULT. CAT MCDONOUGH STRUCK A DEAL WITH PROSECUTORS THIS SUMMER, PLEADING GUILTY TO HINDERING THE PROSECUTION, AND TAMPERING WITH A WITNESS. SHE WAS SENTENCED TO ONE AND A HALF TO THREE YEARS IN PRISON AND AGREED TO TESTIFY AGAINST MAZZAGLIA. BUT EXPERTS SAY THE STATE MAY STILL HAVE TO PUT UP/STRONG CASE TO CONVINCE THE JURY BEYOND A REASONABLE DOUBT. WOULD IT BE VERY DIFFICULT FOR THE STATE TO DISPROVE, FOR EXAMPLE, IF HE SAID IT HAPPENED ACCIDENTALLY OR IF THEY WERE ENGAGED IN SOME TYPE OF DRUG USE, AND SHE DIED AS A RESULT OF THAT AND HE GOT SCARED. MAZZAGLIA IS CHARGED WITH SECOND DEGREE MURDER DEGREE MURDER, AND EVIDENCE AGAINST HIM IS MOUNTING AFTER JAIL HOUSE LETTERS WERE RELEASED THAT ALLEGEDLY OUTLINE AN ELABORATE PLAN TO FRAME AND KILL A WITNESS TO LIZZI'S MURDER. THE LETTERS WILL BE PRESENTED TO THE JURY IN THE TRIAL SET TO BEGIN NEXT MAY. THIS HIGH PROFILE AND SALACIOUS CASE WILL COMMAND HEADLINES AND HEAVY MEDIA COVERAGE AGAIN NEXT YEAR. A REALITY THAT IS PAINFULLY COMMON FOR FAMILIES OF HOMICIDE VICTIMS. YOU'D LIKE TO THINK THAT THE CRIMINAL JUSTICE SYSTEM SOMETIMES BRINGS CLOSURE TO PEOPLE IN THEIR POSITION, THE FAMILY OF THE VICTIM. MANY TIMES IT DOESN'T, ESPECIALLY IN A CASE LIKE THIS WHERE THERE WILL BE A LOT OF UNANSWERED QUESTIONS. NOW THEY'RE UNANSWERED AND THEY'LL BE UNANSWERED AFTER THE TRIAL. THE ATTORNEY GENERAL'S OFFICE DECLINED OUR REQUEST FOR AN INTERVIEW STATING THEY WILL LET THE CASE STAND ON ITS OWN MERIT WHEN IT GOES TO TRIAL IN MAY